TWI382646B - Maximum power point tracking control method for voltage-detection based dc/ac inverter - Google Patents

Description

Control of voltage-controlled DC/AC power converters with maximum power tracking method

The present invention relates to a method of controlling a voltage controlled DC/AC power converter, and more particularly to a method of controlling a DC/AC power converter having a power conversion device for solar cell maximum power tracking.

As the greenhouse gas emissions of countries around the world are limited by the Kyoto Protocol, and the cost of petrochemical energy is becoming more and more expensive, the cost of renewable energy is decreasing, resulting in the regenerative power generation technology with low pollution and low greenhouse gas emissions. Received worldwide attention. Among them, solar power generation with more mature technology and more developmental and forward-looking technology has attracted the most attention.

In the field of solar power generation, in order to improve the effective application of solar energy, in addition to the improvement of solar cell efficiency or the development of new technologies, the maximum power tracking technology is another key core technology, and the "perturbation observation method" is The most popular technology in the largest power tracking technology. A conventional power conversion device using a perturbation observation method, as disclosed in U.S. Patent No. 5,327,071, utilizes a DC/DC (DC/DC) power converter to track the maximum power of a solar battery. The DC/DC power converter continuously adds a disturbance voltage to the output voltage of the solar battery group, and detects an output voltage and an output current of the DC/DC power converter to calculate the DC/DC power converter. The output power, in turn, obtains a detection data. After detecting the second detection data, a controller compares the current detection data of the output power of the DC/DC power converter with the previous detection data, and then determines to join the solar battery. Group loss The disturbance voltage in the output voltage is positive or negative (ie, the disturbance direction of the output voltage of the solar cell group is determined), and the disturbance voltage is adjusted according to the comparison result of the controller, and the output voltage of the solar battery group is disturbed again. Thereby, once the output voltage of the solar battery group is a voltage operating point of the solar battery pack having the maximum output power, the continuously adjusted disturbance voltage can be used to make the output voltage of the solar battery group be near the voltage operating point. Perturbs back and forth to obtain the maximum power of the solar array.

Another conventional power conversion device using a disturbance observation method, as disclosed in U.S. Patent No. 5,932,994, which also utilizes a DC/DC power converter to continuously control the output voltage of a solar battery pack to track the maximum output of the solar battery pack. The voltage operating point of power. First, a disturbance amount is added to the duty cycle of the power switching element of the DC/DC power converter, and the output voltage and the output current of the solar battery group are detected to calculate the output power of the solar battery group, thereby obtaining A detection data. After detecting the second detection data, a controller compares the current detection data of the output power of the solar battery with the previous detection data to determine to join the DC/DC power converter. The disturbance amount in the duty cycle of the power switching element is positive or negative (ie, it is determined that the duty cycle ratio of the power switching element needs to be increased or decreased), and the disturbance amount is adjusted according to the comparison result of the controller, and the disturbance is again disturbed. The duty cycle of the power switching components of the DC/DC power converter. Thereby, once the output voltage of the solar battery group is a voltage operating point of the solar battery group having the maximum output power, the continuous adjustment of the disturbance amount can be used to make the output voltage of the solar battery group be near the voltage operating point. Perturbs back and forth to obtain the maximum power of the solar array.

However, the above two conventional power conversion devices using the disturbance observation method need to detect more than two voltage or current signals, resulting in disadvantages such as high complexity and high manufacturing cost of the control circuit.

In addition, as disclosed in the Republic of China Patent No. I232361, it adds an adjustment amount to the output current of a DC/AC power converter, and detects a DC output voltage variation corresponding to a DC output voltage of a solar battery; or An adjustment amount is added to the DC output voltage of the solar battery, and an output current variation corresponding to the output current of the DC/AC power converter is detected. Finally, the adjustment direction of the adjustment amount is corrected to be in the same direction as the DC output voltage change amount or the output current change amount, and the above steps are continuously repeated to achieve an operation point for tracking the solar battery pack having the maximum power. purpose.

Although the third conventional power conversion device has a simpler circuit architecture than the two conventional power conversion devices described above, it is necessary to detect or adjust the communication of the DC/AC power converter by a current detector. The amplitude of the current at the output is also only applicable to current-controlled power converters. Although the current renewable energy power converter technology mostly uses current control, if it is to be operated as a hybrid power generation system by the conventional current-controlled power converter, one more voltage loop must be used to control the power converter output. Voltage. On the contrary, the conventional voltage-controlled power converter must use amplitude and phase dual-loop control for the output voltage of the power converter. The control circuit is obviously complicated, and there are transient response characteristics caused by the dual-loop control. Poor and other shortcomings. For the above reasons, it is necessary to further improve the above-described conventional power conversion device for maximum power tracking for a solar power generation system and a control method therefor.

The main object of the present invention is to provide a DC/AC power converter control method for a power conversion device with maximum power tracking, so as to control the voltage amplitude on a connected inductor and observe the change of the DC voltage outputted by a solar battery pack. And track the maximum power operating point of the solar array.

In order to achieve the foregoing object, the technical means applied by the present invention comprises: a control method of a voltage controlled DC/AC power converter with maximum power tracking, which is: detecting a first AC voltage detector The voltage of the AC power system is sent to a bandpass filter, and the center frequency of the bandpass filter is the fundamental wave frequency of the AC power system, so that the bandpass filter obtains the fundamental wave component of the AC power system, wherein The fundamental wave component is a sine wave signal; the sine wave signal generated by the band pass filter is phase-shifted by 90 degrees by a phase shift circuit; the sine wave signal after a phase shift of 90 degrees by a multiplier And multiplying an output signal of a maximum power tracking control circuit to obtain a vertical vector signal; adding an vertical vector signal to the voltage signal detected by the first AC voltage detector by an adder to obtain an output voltage a reference signal; detecting, by a second AC voltage detector, an output voltage of the DC/AC power converter and sending it to an input of one of the subtractors, the other of the subtractors The input terminal is connected to the adder, and the subtractor subtracts the output voltage reference signal from the output voltage of the DC/AC power converter; receiving, by a waveform control circuit, the output signal of the subtractor and forming a tone Changing the signal; receiving the modulated signal outputted by the waveform control circuit by a pulse width modulation circuit and sending the signal to a driving circuit, the driving circuit generating a set of driving signals to control the power electronic switch of the DC/AC power converter group. Thereby, the control method controls an output voltage of an output filter of the DC/AC power converter by controlling a voltage on a connected inductor; the voltage on the connected inductor is perpendicular to a fundamental frequency of the AC power system. Voltage, so that the DC/AC power converter outputs a sine wave output current in phase with the fundamental frequency voltage of the AC power system to send a real power injection into the AC power system, so the DC/AC power The converter's maximum power tracking control circuit controls the amplitude of its output current to control the actual output of the DC/AC power converter.

In addition, for the control method, the output signal generated by the maximum power control circuit is obtained by the following steps: a first signal input step, which presets an initial value of an output signal of the maximum power tracking control circuit and a variation, wherein the variation is a difference between a current output signal and a previous output signal, and the initial value of the output signal is sent to a multiplier of the DC/AC controller, the output The signal controls the voltage amplitude on the connected inductor, and detects the initial value of the DC voltage outputted by the solar battery after a delay time; a first iterative operation step defines that the previous output signal is equal to the output An initial value of the signal, and defining a previous DC voltage equal to an initial value of the DC voltage; a signal input step of calculating the current output signal, and replacing the previous change amount by the value of the change amount, And sending the current output signal to the multiplier, and detecting the DC voltage output by the solar battery group after the delay time, and then Defining the obtained DC voltage as a current DC voltage, wherein the value of the next output signal is the sum of the change amount and the previous output signal; and an adjustment direction determining step, which compares the previous time The DC voltage and the current DC voltage, if the current DC voltage is greater than or equal to the previous DC voltage, the change amount is set to be equal to the positive value of the previous change amount, and if the DC voltage is the next time When the DC voltage is less than the previous DC voltage, the amount of change is set to be equal to the negative value of the previous change amount; and an iterative operation step is defined to define that the previous output signal is equal to the current output signal, and defines the former After the DC voltage is equal to the current DC voltage, and the current output signal is obtained, the signal input step is re-executed, wherein the value of the next output signal is the change amount and the previous output signal. with.

Thereby, the voltage control with maximum power tracking of the present invention is a control method of the DC/AC power converter, which can detect the current without using any current detector, has the advantages of simplifying the circuit and reducing the cost, and can still track the solar energy. The maximum power operating point of the battery pack causes the current generated by the solar battery pack and injected into the AC power system to approach the unit power factor.

The above and other objects, features, and advantages of the present invention will become more apparent from the aspects of the appended claims. It is a schematic diagram of a power conversion device used in a solar power generation system using the power conversion device of the present invention for controlling the voltage-controlled DC/AC power converter with maximum power tracking. Please refer to FIG. 1 , which includes a solar battery unit 1 , the power conversion device 2 and an AC power supply system 3 , wherein the power conversion device 2 includes a DC/DC [DC/DC] power converter 4 and a DC/AC [DC/AC] power converter 5. The solar battery unit 1 is connected to one input side of the DC/DC power converter 4, and an output side of the DC/DC power converter 4 is connected to the DC/AC [DC/AC] power converter 5 An input side is connected to the AC power supply system 3 by an output side of the DC/AC power converter 5. In this way, one of the DC power outputted by the solar battery unit 1 can be converted to the AC power supply system 3 via the power conversion device 2; more specifically, the DC/DC power converter 4 of the power conversion device 2 is The voltage level adjustment is performed for the DC voltage of the DC power outputted by the solar battery unit 1, and the DC/AC power converter 5 of the power conversion device 2 outputs the DC power output by the DC/DC power converter 4. It is converted into an alternating current electric energy to be injected into the alternating current power supply system 3. The output DC voltage of the DC/DC power converter 4 may also vary according to the change of the AC voltage of the AC power system 3.

Please refer to FIG. 2 , which is a schematic diagram showing the circuit structure of the DC/DC power converter 4 of the power conversion device 2 , wherein the DC/DC power converter 4 is a boost converter. It includes an input capacitor 41, an inductor 42, a power electronic switch 43, a diode 44, an output capacitor 45, and a DC/DC control unit 46. Referring to FIGS. 1 and 2, the two ends of the input capacitor 41 form two input terminals of the DC/DC power converter 4, and the input capacitor 41 is connected in parallel to the two DC output terminals of the solar battery unit 1. In order to stabilize the DC voltage outputted by the solar battery unit 1; one end of the inductor 42 is connected to the positive terminal of the input capacitor 41, and the other end of the inductor 42 is connected to the power electronic switch 43 and the diode 44. The anode end [Anode end] is connected; the cathode end [cathode end] of the diode 44 is connected to the positive terminal of the output capacitor 45; the negative terminal of the input capacitor 41, the negative terminal of the output capacitor 45 and the power The other ends of the electronic switch 43 are connected together; and the two ends of the output capacitor 45 form two outputs of the DC/DC power converter 4; and the DC/DC control unit 46 is connected to the power electronic switch 43. In order for the DC/DC control unit 46 to generate a control signal to control the power electronic switch 43 to assume an on or off state. Thereby, when the DC/DC control unit 46 activates the power electronic switch 43 to be in an on state, the DC power generated by the solar battery unit 1 charges and stores the inductor 42; and when the DC When the /DC control unit 46 activates the power electronic switch 43 to be in an off state, the electrical energy pre-stored by the inductor 42 is released to the output capacitor 45 via the diode 44. Thereby, the electric energy of the solar battery unit 1 can be boosted, and the DC power generated by the fluctuation can be regulated and converted to DC power having a higher voltage level.

Referring to FIG. 3, it is a control block diagram showing the DC/DC control unit 46 of the DC/DC power converter 4. The DC/DC control unit 46 includes a DC voltage detector 461, a first subtractor 462, a PI [proportional integral] controller 463, a first PWM [Pulse Width Modulation] circuit 464, and a first driver. Circuit 465. The DC/DC control unit 46 controls the output DC voltage of the DC/DC power converter 4 by using a closed loop control method, so that the output DC voltage is presented as a fixed value without being output by the solar battery unit 1. The change in DC voltage changes. The DC voltage detector 461 is connected to an input end of the first subtractor 462, and the DC voltage detector 461 is configured to detect an output DC voltage of the DC/DC power converter 4 and send the first DC subtraction The other input end of the first subtractor 462 is configured to input a predetermined voltage, so that the first subtractor 462 subtracts the preset voltage from the output DC voltage; the input of the PI controller 463 The end is connected to the output end of the first subtractor 462, so that the PI controller 463 calculates the DC current control signal by using the operation result of the first subtractor 462; the first PWM circuit 464 is connected to the PI controller 463 and Between the first driving circuit 465, the PI controller 463 sends the generated DC control signal to the first PWM circuit 464 to generate a pulse wave signal, and the duty cycle of the pulse wave signal is proportional to the DC control signal. Then, the pulse signal is input to the first driving circuit 465 to generate a driving signal, thereby controlling the power electronic switch 43 of the DC/DC power converter 4.

Referring to FIG. 4, it is a schematic diagram showing the circuit architecture of the DC/AC power converter 5 of the power conversion device 2. The DC/AC power converter 5 includes a power electronic switch group 51, an output filter 52, a coupled inductor 53 and a DC/AC [DC/AC] control unit 54, wherein the DC/AC control unit 54 is used. The control method of the present invention operates. The power electronic switch group 51 can be selected as a full-bridge power electronic switch group or a half-bridge power electronic switch group, and the power electronic switch group 51 has two DC input terminals and two AC output terminals, and the two DC input terminals Connected to the two ends of the output capacitor 45 of the DC/DC power converter 4, and the two AC outputs are connected to the output filter 52; the output filter 52 also has two inputs and two outputs, wherein The two input terminals are connected to the power electronic switch group 51, and the output filter 52 is preferably composed of a capacitor 521 and an inductor 522. The capacitor 521 is connected to the output filter 52. Between the output terminals, one end of the inductor 522 is connected to one of the two input ends of the output filter 52, and the other end thereof is connected to one of the two output ends; one end of the connection inductor 53 is connected to the output filter One of the outputs of the two of the switches 52, and the other end of the connecting inductor 53 forms one end of the output side of the DC/AC power converter 5, and the other output of the output of the output filter 52 forms the other end DC/AC power converter 5 The other end of the output side; the DC/AC control unit 54 is connected to each power electronic switch of the power electronic switch group 51, so that the DC/AC control unit 54 generates a set of control signals to control each of the power electronic switch groups 51. The power electronic switches are respectively turned on or off. Thereby, the DC/AC power converter 5 can perform maximum power tracking on the output power of the solar battery group 1 by using the control signal generated by the DC/AC control unit 54 of the present invention, so as to obtain higher power conversion. The AC power is injected into the AC power system 3.

Referring to FIG. 5, a control block diagram of a control method of a voltage-controlled DC/AC power converter with maximum power tracking according to a preferred embodiment of the present invention is implemented by the DC/AC control unit 54, wherein The DC/AC control unit 54 is voltage controlled. The DC/AC control unit 54 includes a first AC voltage detector 540, a band pass filter 541, a phase shift circuit 542, a multiplier 543, an adder 544, and a second AC voltage detector 545. A second subtractor 546, a waveform control circuit 547, a second PWM [pulse width modulation] circuit 548 and a second driving circuit 549. The first AC voltage detector 540 is connected to the band pass filter 541, so that the first AC voltage detector 540 detects the voltage of the AC power system 3 and sends it to one of the input terminals of the band pass filter 541. The output of the band pass filter 541 is connected to the phase shift circuit 542, and the center frequency of the band pass filter 541 is selected as the fundamental wave frequency of the AC power system 3, so that the band pass filter 541 is obtained. The fundamental frequency component of the AC power system 3, that is, the bandpass filter 541 outputs a sine wave signal, and the sine wave signal is at the same frequency and in phase with the voltage of the AC power system 3; the phase shift circuit 542 will The sine wave signal outputted by the band pass filter 541 is sent to one input of the multiplier 543 after being advanced by 90 degrees, and the other input end of the multiplier 543 is supplied to one of the maximum power tracking control circuits 55. Outputting a signal input, and multiplying the sine wave signal after the 90 degree phase shift and the output signal of the maximum power tracking control circuit 55 by the multiplier 543 to obtain a vertical vector signal, wherein the vertical vector signal is Leading the AC The voltage of system 3 is one sine wave of 90 degrees, and the amplitude of the vertical vector signal is determined by the output signal of the maximum power tracking control circuit 55, and the amplitude of the output current of the DC/AC power converter 5 will be proportional to the vertical The amplitude of the vector signal; the adder 544 adds the vertical vector signal to the voltage signal detected by the first AC voltage detector 540 to obtain an output voltage reference signal; and the second AC voltage detector 545 is configured to detect the output voltage of the output filter 52; the second input of the second subtractor 546 is respectively connected to the output of the adder 544 and the second AC voltage detector 545, and the second subtraction The output of the 546 is connected to the waveform control circuit 547, so that the second subtractor 546 subtracts the output voltage reference signal from the output voltage of the output filter 52 and sends it to the waveform control circuit 547 to form a tone. Changing the signal, thereby completing the closed loop control of the output voltage of the output filter 52; finally, the modulated signal output by the waveform control circuit 547 is sent to the second drive via the second PWM circuit 548 Circuit 549 controls the power electronic switch bank 51 of the DC/AC power converter 5 to generate a set of drive signals. Wherein, the waveform control circuit 547 has a faster response speed, and the output voltage of the output filter 52 is controlled to the output voltage reference signal, and the voltage of the connection inductor 53 is equal to the voltage of the AC power system 3 and the The difference between the output voltages of the output filter 52 of the DC/AC power converter 5, the voltage of the connected inductor 53 may be toward the vertical vector signal, which is a sine wave voltage that is 90 degrees ahead of the AC power system 3 Therefore, a fundamental frequency sine wave output current that is in phase with the voltage of the AC power system 3, that is, an output current of the DC/AC power converter 5 can be generated on the connection inductor 53. Therefore, for the power conversion device with maximum power tracking of the present invention, it is only necessary to detect the change of the DC voltage formed by the solar battery 1 in the input capacitor 41, and to switch through the power electronic switch group 51. By controlling the vertical voltage amplitude on the connection inductor 53, the power conversion device 2 of the present invention can achieve the purpose of maximum power tracking.

Please refer to FIG. 6, which is a flowchart showing the maximum power tracking method adopted by the maximum power tracking control circuit 55 of the DC/AC control unit 54 of the present invention. First, the initial value of the output signal of the maximum power tracking control circuit 55 is defined as K(0), and the output signal of the second time is K(n), and the previous output signal is K(n-1), and the current output is The amount of change between the previous output signals is ΔK(n), and the time interval between the current and previous output signals is a delay time T. According to the above, the output signal that can be summarized is: K(n)=K(n-1)+ΔK(n). As shown in FIG. 5, the output signal is sent to the multiplier 543 of the DC/AC control unit 54 to determine the magnitude of the amplitude of the vertical vector signal, thereby determining the voltage amplitude of the coupled inductor 53 and the DC. The amplitude of the output current of the /AC power converter 5, and the output power of the DC/AC power converter 5 is proportional to the amplitude of its output current. In addition, the maximum power tracking control circuit 55 detects the DC voltage output by the solar battery unit 1 and defines an initial value of the detected DC voltage as Vpv(0), and the next DC voltage is Vpv(n). ), and the previous DC voltage is Vpv(n-1).

As described above, each time the output signal output by the maximum power tracking control circuit 55 is obtained by the following steps. The maximum power tracking control circuit 55 first performs a first signal input step S1. This step pre-sets the values of K(0) and ΔK(n), and sends the initial value K(0) of the output signal to The multiplier 543 detects the initial value Vpv(0) of the DC voltage output from the solar battery unit 1 after the delay time T elapses after the initial value K(0) is sent. Subsequently, the maximum power tracking control circuit 55 performs a first iterative operation step S2, which defines that the previous output signal K(n-1) is equal to the initial value K(0) of the output signal, and defines the The previous DC voltage Vpv(n-1) is equal to the initial value Vpv(0) of the DC voltage. After the first iterative operation step S2 is completed, the maximum power tracking control circuit 55 performs a signal input step S3, which is calculated by K(n)=K(n-1)+ΔK(n). The output signal K(n) is substituted for the previous change amount ΔK(n-1) by the value of the change amount ΔK(n), and the next output signal K(n) is sent to the multiplier 543. And after the delay time T, the DC voltage outputted by the solar battery unit 1 is detected again, and the obtained DC voltage is defined as the current DC voltage Vpv(n). Then, an adjustment direction determining step S4 is performed. In this step S4, the previous DC voltage Vpv(n-1) and the next DC voltage Vpv(n) are compared to determine whether to increase or decrease the vertical vector signal. The amplitude. More specifically, when Vpv(n) ≧ Vpv(n-1), the change amount ΔK(n) is set to be equal to the positive value of the previous change amount ΔK(n-1) to maintain the The direction of the change of the amplitude of the vertical vector signal is unchanged; and when Vpv(n) < Vpv(n-1), the change amount ΔK(n) is set equal to the previous change amount ΔK(n-1) The negative value is such that the amplitude of the vertical vector signal changes in the opposite direction. Finally, performing an iterative operation step S5, defining that the previous output signal K(n-1) is equal to the current output signal K(n), and defining the previous DC voltage Vpv(n-1) is equal to the The second DC voltage Vpv(n) is calculated by K(n)=K(n-1)+ΔK(n) to obtain the current output signal K(n), and then continue to perform the above steps. S3 to step S5. Thereby, when the DC voltage outputted by the solar battery unit 1 is adjusted to be close to the maximum power operating point by adjusting the amplitude of the vertical vector signal, the DC voltage outputted by the solar battery unit 1 continues to be disturbed back and forth.

In summary, the control method of the DC/AC control unit 54 applied to the power conversion device 2 of the present invention only needs to control the connection by a single loop, compared to the power conversion device that is used for maximum power tracking by the disturbance observation method. The amplitude of the voltage on the inductor 53 and observing the change of the DC voltage outputted by the solar battery unit 1, and controlling the solar battery unit 1 to operate at the maximum power without using any current detector The operating point is converted into the AC power supply system 3 by converting the maximum power generated by the solar battery unit 1 into an AC power that tends to be a unit of power. Therefore, the power conversion device 2 using the control method of the present invention has a simplified circuit and a cost reduction effect.

While the invention has been described in connection with the preferred embodiments described above, it is not intended to limit the scope of the invention. The technical scope of the invention is protected, and therefore the scope of the invention is defined by the scope of the appended claims.

1. . . Solar battery pack

2. . . Power conversion device

3. . . AC power system

4. . . DC/DC power converter

41. . . Input capacitor

42. . . Inductor

43. . . Power electronic switch

44. . . Dipole

45. . . Output capacitor

46. . . DC/DC control unit

461. . . DC voltage detector

462. . . First subtractor

463. . . PI controller

464. . . First PWM circuit

465. . . First drive circuit

5. . . DC/AC power converter

51. . . Power electronic switch group

52. . . Output filter

521. . . capacitance

522. . . inductance

53. . . Connecting inductance

54. . . DC/AC control unit

540. . . First AC voltage detector

541. . . Band pass filter

542. . . Phase shift circuit

543. . . Multiplier

544. . . Adder

545. . . Second AC voltage detector

546. . . Second subtractor

547. . . Waveform control circuit

548. . . Second PWM circuit

549. . . Second drive circuit

55. . . Maximum power tracking control circuit

S1. . . First signal input step

S2. . . First iteration step

S3. . . Signal input step

S4. . . Adjustment direction decision step

S5. . . Iterative operation step

Fig. 1 is a schematic view showing the construction of a power conversion device using a control method of a voltage-controlled DC/AC power converter with maximum power tracking according to the present invention.

Fig. 2 is a circuit diagram showing the circuit structure of a DC/DC power converter of a power conversion device to which a control method of a voltage-controlled DC/AC power converter having maximum power tracking is applied.

Figure 3 is a control block diagram of a DC/DC control unit of a power conversion apparatus to which the control method of the voltage-controlled DC/AC power converter of the present invention is applied.

Fig. 4 is a circuit diagram showing the circuit configuration of a DC/AC power converter of a power conversion device to which a control method of a voltage-controlled DC/AC power converter having maximum power tracking is applied.

Figure 5 is a control block diagram of a method of controlling a voltage controlled DC/AC power converter with maximum power tracking in accordance with a preferred embodiment of the present invention.

Figure 6 is a flow chart showing the maximum power tracking method employed by the maximum power tracking control circuit of the voltage controlled DC/AC power converter with maximum power tracking in accordance with a preferred embodiment of the present invention.

54. . . DC/AC control unit

540. . . First AC voltage detector

541. . . Bandpass filter

542. . . Phase shift circuit

543. . . Multiplier

544. . . Adder

545. . . Second AC voltage detector

546. . . Second subtractor

547. . . Waveform control circuit

548. . . Second PWM circuit

549. . . Second drive circuit

55. . . Maximum power tracking control circuit

Claims (2)

A control method for a voltage-controlled DC/AC power converter with maximum power tracking, comprising: detecting a voltage of an AC power system by a first AC voltage detector, and sending the voltage to a band pass filter, and the band The center frequency of the pass filter is the fundamental wave frequency of the AC power system, so that the band pass filter obtains the fundamental wave component of the AC power system, wherein the fundamental wave component is a sine wave signal; The sine wave signal generated by the band pass filter is subjected to a phase shift of 90 degrees; a multiplier is used to multiply the sine wave signal after 90 degree phase shift and the output signal of a maximum power tracking control circuit to obtain a vertical vector a signal; an adder adds the vertical vector signal to the voltage signal detected by the first AC voltage detector to obtain an output voltage reference signal; and detects a continuous current by a second AC voltage detector /the output voltage of the output filter of the AC power converter is sent to one of the input terminals of the subtractor, the other input of the subtractor is connected to the adder, and the subtractor is The output voltage reference signal is subtracted from the output voltage of the DC/AC power converter; a waveform control circuit receives the output signal of the subtractor and forms a modulated signal; and receives the waveform by a pulse width modulation circuit. The modulation signal outputted by the control circuit is sent to a driving circuit, which generates a set of driving signals to control the power electronic switch group of the DC/AC power converter. The control method of the voltage-controlled DC/AC power converter with maximum power tracking according to Item 1 of the patent application scope, wherein the output signal generated by the maximum power tracking control circuit is obtained by the following steps: a first signal An input step of presetting an initial value and a change amount of an output signal of the maximum power tracking control circuit, wherein the change amount is a difference between a current output signal and a previous output signal, Sending an initial value of the output signal to the multiplier, and detecting an initial value of a DC voltage outputted by a solar battery pack after a delay time; a first iterative operation step, the step defining the previous time The output signal is equal to the initial value of the output signal, and defines a previous DC voltage equal to the initial value of the DC voltage; a signal input step, the step of calculating the current output signal, and replacing the value of the change a previous change amount, and the current output signal is sent to the multiplier, and the solar cell is detected after the delay time The output DC voltage is defined as a current DC voltage, wherein the value of the current output signal is the sum of the change amount and the previous output signal; an adjustment direction determining step The first step is to compare the previous DC voltage with the current DC voltage. If the current DC voltage is greater than or equal to the previous DC voltage, the change amount is set equal to the previous change amount, and If the current DC voltage is less than the previous DC voltage, the change amount is set to be equal to the negative value of the previous change amount; and an iterative operation step, the step is to define that the previous output signal is equal to the current time. And outputting the signal, and defining the previous DC voltage to be equal to the current DC voltage, and calculating the current output signal, and then performing the signal input step again, wherein the value of the current output signal is the change amount And the sum of the previous output signals.